Amelioration of inflammatory myopathies by glucagon-like peptide-1 receptor agonist via suppressing muscle fibre necroptosis.
Level 5 - mechanism / opinion, no new human data
Preclinical in vitro, animal model, and descriptive human tissue study
PubMed 35775116 · doi:10.1002/jcsm.13025
What was done
Researchers evaluated GLP-1 receptor (GLP-1R) expression in muscle biopsy specimens from patients with polymyositis (PM) and in a murine model of C-protein-induced myositis (CIM). They tested the therapeutic effect of the GLP-1R agonist PF1801, administered either alone or in combination with prednisolone (PSL), on grip strength, muscle fiber cross-sectional area, histological inflammation scores, and serum inflammatory markers (TNFα, IL-6, HMGB1) in CIM mice. In vitro mechanisms were investigated in FASLG-treated C2C12-derived myotubes to assess necroptosis pathways, AMPK activation, PGAM5 degradation, and antioxidant gene expression.
What was found
GLP-1R was expressed on inflamed muscle fibers in PM patients and CIM mice. In the CIM mouse model, PF1801 monotherapy and combination therapy significantly improved outcomes compared with vehicle: - Grip strength (mean ± SD): PF1801 227 ± 6.0 g (P < 0.01) and PF1801 + PSL 224 ± 8.5 g (P < 0.01) vs. Vehicle 162 ± 6.0 g. - Muscle fiber cross-sectional area: PF1801 1896 ± 144 μm² (P < 0.05) and PF1801 + PSL 2018 ± 445 μm² (P < 0.01) vs. Vehicle 1349 ± 199 μm². - Histological inflammation scores (median, IQR): PF1801 0.0, 0.0–0.5 (P < 0.05) and PF1801 + PSL 0.0, 0.0–0.0 (P < 0.01) vs. Vehicle 1.9, 1.3–3.3. PF1801 lowered serum levels of TNFα, IL-6, and HMGB1. Mechanistically in myotubes, PF1801 inhibited necroptosis via AMPK activation, promoted proteasomal degradation of PGAM5, and reduced reactive oxygen species accumulation by upregulating antioxidant genes (Nfe2l2, Hmox1, Gclm, Nqo1).
Why it matters
This study identifies GLP-1R as a potential target in inflammatory myopathies, showing that GLP-1R agonism can reduce muscle inflammation and prevent necroptosis-driven muscle weakness without causing glucocorticoid-like muscle atrophy in preclinical models.
Limits
Findings are derived primarily from cell cultures and a rodent disease model, with human data limited to descriptive receptor expression in biopsy samples. Sample sizes for human specimens and animals were not reported in the abstract. Clinical efficacy, safety, and optimal dosing in human polymyositis patients remain unmeasured.
Cited by
- contradicts GLP-1 receptor agonists ramp up AMPK, which can cause muscle wasting in people who do not consume adequate protein.